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9 Cards in this Set

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Ksp
solubility product
saturated
solution is saturated when the dissolution rxn is at equilibrium and no more solid appears to dissolve
B/c amount of tetraborate is related to ____, we can...
-related to the amount of OH-
-if we can determine the number of OH- ions in solution, we know the amount of tetraborate ions
-use titration to count # of OH- ions in solution (add H+ ions through strong acid HCl until we've added 1 H+ for each OH- present
-the point where all the OH- is used up (converted to water) is the titration's eq. pt.
-to find this, we will use an acid/base indicator that will change color when the OH- ions are gone
-at this point, the # of OH- ions initially present = # H+ ions we've added
-find # of H+ ions added from volume and concentration of the acid used
Once we know tetraborate concentration...
we can calculate the Ksp for borax using the equilibrium expression for the dissolution
By performing titrations of borax solutions at different temperatures...
we can measure the temp dependence of Ksp and find delta G, deltaH, deltaS (naught)
deltaG (naught) equations
dG = dH - TdS
(d=delta)
(naught on G, H, S)

dG=-RTln(K)
ln(K) equation
ln(K) = -(dH/R)(1/T) + dS/R
y=mx+b
(naught on H and S)
General info about this experiment
-determine solubility product Ksp for Borax at different temperatures
-create a Van't Hoff plot to calculate the thermodynamic parameters deltaH, deltaS and delta G (naught)
Lab procedure
-each group sets up a saturated borax solution (borax, distilled water) at their assigned temperature (cold solution in ice bath, one at room temp, third warmed on a hot plate)
-let borax solution temp be stable for several min, and solid borax must be present (demonstrating equilibrium)
-get 4 250 mL flasks, put 5 mL borax solution into each one, add distilled water until reaches 250 mL mark
-add 4 drops of bromocresol green indicator --> solution should become a light blue color
-do titrations